Next step

"The next step is to understand how these susceptibility genes affect the immune system, and to keep exploring environmental factors that might alter the risk of type 1 diabetes, which results from an incredibly complex interaction between nature and nurture," says Professor John Todd of Britain's University of Cambridge.

In a commentary in the journal, Dr Robert Plenge of Brigham and Women's Hospital in Boston says the findings, "have implications beyond the shared genetic causes of type 1 diabetes and coeliac disease."

According to Plenge, lupus and rheumatoid arthritis, two other autoimmune diseases, have also been linked in previous studies. He says the findings are likely to lead to new treatments for the conditions.

According to the World Health Organization, at least 171 million people worldwide suffer from diabetes, with between 5% and 10% of them having type 1.

Coeliac disease is estimated to affect about 1% of people of European descent.